Field of the Invention
This invention relates to a device for the removal of residual layers of paper from paper mill roll cores. Such a device is often termed a "core slabber", or core slabbing machine.
In the operation of a paper mill wherein large rolls of paper are unwound from a hollow, reusable core and are cut into smaller lengths, it is customary to unwind nearly all of the paper on a roll and then to remove the almost exhausted paper roll, instead of completely unwinding all of the paper from the core. Such substantially exhausted rolls are of no practical use regarding the residual paper left on them. However, the cores are reusable and it is therefore the practice in this art to remove the residual paper from the cores, so that the cores may be reused.
The prior art includes core slabbing machine constructions, a recent example of which is described in McCay, et al. U.S. Pat. No. 4,506,575, dated Mar. 26, 1985, issued to McCay et al. In the McCay construction, a horizontal, cantilevered mandrel is provided, over which the core to be slabbed is placed. This mandrel is expandable, to thereby frictionally lock or engage the core to the mandrel. A horizontally reciprocating knife is positioned above the mandrel, with a motive power means, shown as a motor and sprocket combination, employed to move the cutting knife horizontally back and forth, to thereby make a number of sequential or repeated passes. With each pass, a plurality of layers of paper of the residual paper on the core is removed, with the action continuing until all of the paper is removed from the core. The core is then removed from the core slabbing machine for reuse.
While apparently operative for the purpose of core slabbing, the McCay structure suffers a disadvantage, in that a special mandrel must be employed. This mandrel is of the expanding type, with the frictional force of expansion derived from the mandrel operating to prevent the core from sliding relative to the mandrel during the paper cutting operation. The knife of the McCay construction exerts a horizontal force on the paper, this force being transferred to the core, which action tends to slide the core relative to the mandrel. Without some means to lock the core to the mandrel, movement of the knife relative to the residual paper to cut it results in at least some movement of the core relative to the mandrel, with consequent impairment of the desired paper cutting action of the knife. Another horizontally reciprocating knife for removing residual paper stock from a reusable core is detailed in U.S. Pat. No. 1,838,011, dated Dec. 22, 1931, issued to St. Peter. Corecentering plugs are required in the apparatus and the cutting knives are reversed manually by a lever.
A machine somewhat similar to the present invention is described in U.S. Pat. No. 3,204,501, dated Sept. 7, 1965, issued to Lane. In that machine, a coreless roll of sheet metal (to be cut and scrapped) is placed on a horizontal, cantilevered, hollow mandrel. Each of a plurality of spaced, freely rotatable cutting wheels is mounted on and carried by an endless motordriven sprocket chain, the arrangement including a linear fluid pressure motor which forces the carriage carrying the cutter wheels downwardly against the radially outermost whorls of the sheet metal strip. The direction of horizontal movement of the cutter wheels is apparently the same at all times, one end of the roll of sheet metal shown as abutting the vertical standard to which one end of the mandrel is affixed, to thereby prevent sliding of the roll. No provision is made in the Lane construction for stopping the operation after the cutting wheels have moved any sensed or predetermined downward distance. There being no core within the sheet metal roll, which is to be protected, there is accordingly, no need for any such provision.